Method for controlling and/or regulating a constant voltage converter for at least two electromagnetic valves of an internal combustion engine, especially an internal combustion engine in a motor vehicle

ABSTRACT

A method for controlling and/or regulating a d.c. converter for at least two electromagnetic valves of an internal combustion engine of a motor vehicle is provided. A current generated by the d.c. converter is supplied to each valve. A determination is made as to when the total currents supplied to the valves constitute a high load for the d.c. converter. If this is the case, the d.c. converter is influenced in the sense of better processing of the high load.

FIELD OF THE INVENTION

The present invention is directed to a method for controlling and/orregulating a d.c. converter for at least two electromagnetic valves ofan internal combustion engine in which each valve is supplied with acurrent generated by the d.c. converter. The present invention alsorelates to a corresponding device for controlling and/or regulating ad.c. converter for at least two electromagnetic valves.

BACKGROUND INFORMATION

It is known that a plurality of electromagnetic valves may be suppliedwith current by a d.c. converter via an output stage. In this context,it is possible for overlapping currents for the different valves toresult in a high load for the d.c. converter as a whole. The d.c.converter must be designed for this high load, which is associated withincreased expenditure under some circumstances.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method in which theexpenditure for processing a high load of the d.c. converter is reduced.

This object is achieved with the method according to the presentinvention by determining when the total currents supplied to the valvesrepresent a high load for the d.c. converter, and if this is the case,by adapting the d.c. converter for improved processing of the high load.The present invention also provides a corresponding device.

The d.c. converter is set to the high load using the present invention.Thus, the d.c. converter is capable of better processing this high load.This in turn entails the advantage that the d.c. converter need nolonger be designed on the basis of the high load but instead may bedesigned by taking into account the better processing according to thepresent invention. In particular, it is possible to select the outputcapacitor of the d.c. converter to be smaller than would be necessary tomatch a high load.

In an advantageous further refinement of the present invention, theoutput voltage of the d.c. converter is increased when there is a highload. The output voltage may be controlled and/or regulated to asetpoint value and the n setpoint value may be increased.

This measure achieves the result that the high load of the d.c.converter results in a lower dip in the output voltage. In particular,as already mentioned, the smaller dip in the output voltage allows asmaller output capacitor of the d.c. converter to be used.

It is particularly advantageous if the increase in the output voltageand/or the setpoint value is already performed before the high loadoccurs. Thus the d.c. converter is prepared for the high load. In thiscase, the output voltage already increases to the full extent when thehigh load occurs and is thus effective.

A further implementation of the present invention includes a computerprogram having program commands suitable for execution of the methodaccording to the present invention when the computer program runs on acomputer. Accordingly, the present invention is implemented by a digitalstorage medium including a computer program having program commandssuitable for executing the method according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic block diagram of an exemplary embodiment of adevice according to the present invention for controlling at least twoelectromagnetic valves of an internal combustion engine.

FIG. 2 shows a schematic wiring diagram for one of the electromagneticvalves with the current flow in four successive time ranges.

FIG. 3 shows a schematic time chart of the current across one of theelectromagnetic valves in the four time ranges.

FIGS. 4 a-4 cshow three schematic time charts of currents and voltagesacross, or at, the electromagnetic valves.

DETAILED DESCRIPTION

FIG. 1 shows a device 10 for controlling at least two electromagneticvalves 11, 12. Electromagnetic valves 11, 12 are provided for use in aninternal combustion engine in a motor vehicle in particular. Forexample, electromagnetic valves 11, 12 may be provided in conjunctionwith an electrohydraulic valve control for the intake and exhaust valvesof the internal combustion engine. In this case, a hydraulic system iscontrolled via electromagnetic valves 11, 12, the intake and exhaustvalves of the internal combustion engine being able to be opened andclosed using the hydraulic system.

It is point ed out here explicitly that device 10 may be used not onlyfor two valves 11, 12 depicted here, but may also be used for any numberof valves through appropriate expansions. It is thus possible to have atotal of 32 solenoid valves for controlling the intake and exhaustvalves of the internal combustion engine in the case of an engine havingfour cylinders.

Two d.c. converters 13, 14, which together form a converter 17, areprovided for supplying power to valves 11, 12. Both d.c. converters 13,14 and thus converter 17 include control means and/or regulating meansfor maintaining the generated output voltages at a predeterminedsetpoint level.

D.c. converter 13 is suitable for generating a booster current on anelectric line 15. Accordingly, d.c. converter 14 is suitable forgenerating a holding current on an electric line 16. The booster currentis greater than the holding current.

An output stage 20, which controls the current flow across valves 11,12, is provided between d.c. converters 13, 14 and valves 11, 12. Thiscontrol takes place via a control unit 19. The function of output stage20, its control, and the generated current flow across valve 11 isexplained in greater detail below in connection with FIG. 2. Theexplanation given there also applies accordingly to the current flowacross valve 12 and the current flow across any additional valve.

FIG. 2 shows lines 15, 16 coming from two d.c. converters 13, 14. Line16 is connected via a diode D1, which is connected in the flowdirection, to one of the two terminals of electromagnetic valve 11. Theother terminal of electromagnetic valve 11 is connected via a diode D2,which is also connected in the flow direction, to line 15. The cathodesof both diodes D1, D2 are interconnected via a switch S1. The anode ofdiode D2 is connected to ground via a switch S2.

Depending on the switch positions of two switches S1, S2, there is adifferent current flow across valve 11. Four different switch positionsresulting in four different current flows in four successive time rangesa, b, c, d may be set using two switches S1, S2. Control unit 19 asalready mentioned controls the positions of two switches S1, S2.

FIG. 3 shows current I_(MV) across electromagnetic valve 11 as afunction of time. In particular, FIG. 3 shows four time ranges a, b, c,d resulting from the four adjustable switch positions of two switchesS1, S2.

In first time range a, both switches S1, S2 are closed. This yieldscurrent flow a, as shown in FIG. 2 and designated accordingly as “a.”The booster current generated by d.c. converter 13 flows across valve11. This current I_(MV) increases to a final value according to FIG. 3and is provided to adjust valve 11 into a preselected end position inany case.

In second time range b, which follows time range a, switch S1 is closedand switch S2 is opened. This yields a current flow as shown in FIG. 2and designated accordingly as “b.” This current flow is known asfree-running. This means that at least a portion of the electric energycontained in electromagnetic valve 11 is dissipated via thisfree-running state. Accordingly, current I_(MV) declines in time range baccording to FIG. 3.

Switch S1 is opened in time range c and switch S2 is closed. This yieldsa current flow like that shown in FIG. 2, where it is designatedaccordingly as “c.” The holding current generated by d.c. converter 14in time range c is sent to valve 11. This holding current is selected sothat the end position reached by valve 11 on the basis of the boostercurrent does not change.

Both switches S1, S2 are opened in time range d, which follows timerange c. This yields a current flow like that shown in FIG. 2 anddesignated accordingly as “d.” This current flow represents quenching ofelectromagnetic valve 11. This means that the energy in electromagneticvalve 11 is dissipated completely to 0. Current I_(MV) then issuing fromvalve 11 flows across diode D2 to d.c. converter 13 in time range d.

FIG. 4 ashows booster current I_(B) for connected valves 11, 12generated by d.c. converter 13, plotted as a function of time t.

On the basis of two or more valves 11, 12 present here, it is possiblefor the booster currents of time ranges a of two or even more valves 11,12 to overlap. Such overlap together with the resulting high boostercurrent is designated by reference numeral 22 in FIG. 4 a.

High booster current 22 results in d.c. converter 13 being exposed tovery high loads. The following is provided for better processing ofthese loads:

Control unit 19 is connected to converter 17 via line 18, in particularto d.c. converter 13, which is responsible for the booster current.Control unit 19 determines when a high load has occurred due tooverlapping booster currents. Control unit 19 is able to derive thisfrom the provided triggerings of switches S1, S2 of output stage 20.

Before a high load occurs, control unit 19 indicates the imminent highload to converter 17, in particular d.c. converter 13. This isaccomplished with the help of a signal S, which is sent from controlunit 19 via line 18 to converter 17.

FIG. 4 b shows signal S plotted as a function of time t. It is apparenthere that signal S is present during a period of time T, which extendsfrom a point in time T1 to a point in time T2. This is designated byreference numeral 23 in FIG. 4 b. Period of time T correspondsapproximately to the period of time during which high booster current 22from FIG. 4 is present.

FIG. 4 c shows output voltage U_(B) of d.c. converter 13 plotted as afunction of time. As mentioned previously, this output voltage U_(B) iscontrolled and/or regulated to a predetermined setpoint value. Thesetpoint value is designated as U_(Bsetpoint) in FIG. 4 c. Controland/or regulation of d.c. converter 13 is designed, for example, so thatoutput voltage U_(B) of d.c. converter 13 varies in a tolerance range of±10% around setpoint value U_(BS).

As FIG. 4 cshows, setpoint value U_(BS) of output voltage U_(B) of d.c.converter 13 is raised during period of time T. This is indicated with adashed line in FIG. 4 c and labeled as 24.

As already mentioned, period of time T of FIG. 4 b begins shortly beforethe rise in high booster current 22 in FIG. 4 a after time T1. As aresult, setpoint value U_(Bsetpoint) also increases just prior to therise in high booster current 22. This increase in setpoint valueU_(Bsetpoint) also yields an increase in output voltage U_(B) of d.c.converter 13, which is shown by a dashed line in FIG. 4 c and isdesignated by reference numeral 25.

After the point in time when booster current I_(B) (which is designatedas 22 in FIG. 4 a) rises, d.c. converter 13 thus supplies an increasedoutput voltage U_(B) (designated as 25). This yields the result thatd.c. converter 13 is able to better process the high load associatedwith the rise in booster current I_(B).

In particular, increased setpoint value U_(Bsetpoint) and resultingincreased output voltage U_(B) result in the dip in this output voltageU_(B) due to high booster current I_(B) being lower than would be thecase without the aforementioned increase. This is shown in FIG. 4 c onthe basis of the curves designated by reference numerals 26, 27. Thecurve resulting from the increase in setpoint value U_(Bsetpoint) isindicated by a dashed line and is designated by reference numeral 26,while the curve that would result without the above-described increasein setpoint value U_(Bsetpoint) is designated by reference numeral 27.

Due to the smaller dip in output voltage U_(B) (designated as 26 in FIG.4 c), it is possible to provide d.c. converter 13 with a lower outputcapacitance than would be necessary without the increase in setpointvalue U_(Bsetpoint). It is likewise possible for the control and/orregulating means contained in converter 17 to take preventive measureson the basis of signal S, namely in particular on the basis of the risein signal S at the beginning of period of time T and to do so as apreventive measure even before the occurrence of a system deviation tocounteract the system deviation that would result on the basis of thehigh booster current. In particular, the control and/or regulating meansmay increase the output power of d.c. converter 13 as a preventivemeasure. Other emergency functions may be implemented via line 18 asfollows:

For example, if d.c. converter 14 fails and if this is detected bycontrol unit 19 via measures not described more closely in the presentcase, control unit 19 may control and/or regulate remaining d.c.converter 13 so that it assumes the function of d.c. converter 14 andadditionally generates the holding current. For example, the outputvoltage of d.c. converter 13 may be pulsed to thereby generate acorresponding holding current.

In the inverse case, control unit 19 may control and/or regulate d.c.converter 14 so that it generates not only the holding current but alsothe booster current. In particular, control unit 19 may increase thesetpoint value of the output voltage of d.c. converter 14. In addition,it may be advisable for control unit 19 to trigger switches S1, S2 at anearlier point in time for generating the booster current to thuscompensate for possible deterioration of the tightening dynamics ofvalves 11, 12.

1-11. (canceled)
 12. A method for regulating a d.c. converter for atleast two electromagnetic valves of an internal combustion engine, themethod comprising: supplying each of the at least two electromagneticvalves with a current that is generated by the d.c. converter;determining when a total current supplied to the at least twoelectromagnetic valves constitutes a high load for the d.c. converter;and if a high load is determined, adapting the d.c. converter forprocessing of the high load.
 13. The method of claim 12, wherein thecurrent supplied to each of the at least two electromagnetic valves isdetermined as a function of a triggering provided for an output stageupstream from the at least two electromagnetic valves.
 14. The method ofclaim 12, wherein the high load for the d.c. converter is derived fromoverlapping currents of the at least two electromagnetic valves.
 15. Themethod of claim 12, wherein adaptation of the d.c. converter includesincreasing an output voltage of the d.c. converter in the case of a highload.
 16. The method of claim 15, wherein the output voltage isregulated with reference to a setpoint value, and wherein the setpointvalue is increased.
 17. The method of claim 12, wherein an output powerof the d.c. converter is increased in the case of a high load.
 18. Themethod of claim 12, wherein an increase in an output voltage of the d.c.converter is performed prior to an occurrence of the high load.
 19. Themethod of claim 17, wherein the increase in the output voltage isterminated upon termination of the high load state.
 20. Acomputer-readable storage medium for storing computer program havinginstructions for controlling, when the program is executed by acomputer, a method comprising: supplying each of the at least twoelectromagnetic valves with a current that is generated by the d.c.converter; determining when a total current supplied to the at least twoelectromagnetic valves constitutes a high load for the d.c. converter;and if a high load is determined, adapting the d.c. converter forprocessing of the high load.
 21. A device for regulating a d.c.converter for at least two electromagnetic valves of an internalcombustion engine in a motor vehicle, a current generated by the d.c.converter being supplied to each of the at least tow electromagneticvalves, the device comprising: a control unit configured to determinewhen a total current supplied to the at least two electromagnetic valvesrepresents a high load for the d.c. converter, wherein the control unitregulates the d.c. converter for optimal processing of the high load.